Screengrab from the Advertising Standards Authority for the gambling website Tombola.
Photograph: ASA/PA

The advertising watchdog has banned gambling ads that ran in ITV’s I’m a Celebrity … Get Me Out of Here app for breaking rules designed to protect children from being encouraged to bet.

The app for the most recent series was sponsored by Tombola, an online bingo, casino and slots company, which ran ads featuring phrases such as: “A chance to win a share of £250,000 for free” when users sign up to vote on the TV show.

Tombola’s sponsorship of the hugely popular show, which drew a peak audience of almost 12 million, with more than 1 million under-18-year-old viewers - has drawn criticism in light of a report that found a sharp rise in the number of children who are problem gamblers.

Users of the app can click through to casino-style “slots” games and other forms of gambling.

“Gambling ads should not be on apps that will clearly be used by kids. It’s simple,” he said.

The ASA launched an investigation to assess whether the ads were in breach of the UK code that protects under-18s from being exposed to gambling ads.

Tombola said it worked with ITV and its media buying agency to ensure the ad campaign was targeting over-18s. Viewing figures for the series showed that 91% of the audience was aged 18 or over.

The ASA said that while the app was not directly targeting under-18s it would still appeal to some young fans of the show, adding that there was no data available relating to the age profile of people who had downloaded the app.

The app, which has been downloaded more than 1m times, also had no mechanism to allow the targeting or blocking of ads being shown to particular age groups.

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“We considered Tombola Arcade should not have used the app to deliver gambling ads to consumers,” the ASA said. “We therefore considered the advertiser had not taken sufficient care, through the selection of media, to ensure that the ads were directed at an audience aged 18 and over so as to minimise under-18s’ exposure to them.”

Marc Etches, chief executive of the UK’s leading gambling charity GambleAware, said: “Thankfully, on this occasion, common sense has prevailed and the advert has been removed.

“Unfortunately, this isn’t always the case and with 55,000 11- to 16-year-olds now classed as problem gamblers, it is clear more needs to be done to address this serious public health issue.”